Fig. 2: The physicochemical and electrochemical adaptation verification of ULCE toward low temperature.

a FTIR spectra of various solutions and electrolytes. b Optical photos of three electrolytes in ultra-low temperature environment. c DSC test of ULAE and ULCE from −90 to 45 °C. d The ionic conductivities of ULAE and ULCE in the temperature range of −80 to 20 °C. e Arrhenius curves and a comparison of activation energies (Ea) for the de-solvation process of Zn2+ in ULAE and ULCE. f Transference number of Zn2+ in ULLE and ULCE. The in-situ cooling-Raman spectra of g ULAE from 20 °C to −40 °C and I ULCE from 20 °C to −80 °C. Raman mapping of h ULAE and j ULCE during the cooling process from 20 °C to −80 °C.